Solar flares are huge eruptions of energy on the sun and often produce clouds of plasma traveling more than a million miles an hour. When these clouds reach Earth they can cause radio communications blackouts, disruptions to electric power grids, errors in GPS navigation, and hazards to satellites and astronauts. The EXIS instrument on NOAA’s GOES-16, built by the University of Colorado’s Laboratory for Atmospheric and Space Physics in Boulder, Colorado, measures solar flares at several wavelengths and improves upon current capabilities by capturing larger flares, measuring the location of the flares on the sun, and measuring flares in more wavelengths. The GOES-16 EXIS will provide forecasters at the NOAA’s Space Weather Prediction Center with early indications of impending space weather storms so they can issue alerts, watches and warnings.

The figure shows an example of EXIS observations at two different wavelengths of a flare that peaked at 11:05 UTC [6:05 a.m. EST] on January 21, 2017. This is a relatively small flare, yet the brightness of the sun in soft (lower energy) X-rays increased by a factor of 16. EXIS will give NOAA and space weather forecasters the first indication that a flare is occurring on the sun, as well as the strength of the flare, how long it lasts, the location of the flare on the sun, and the potential for impacts here at Earth.

NASA successfully launched GOES-R at 6:42 p.m. EST on November 19, 2016 from Cape Canaveral Air Force Station in Florida and it was renamed GOES-16 when it achieved orbit. GOES-16 is now observing the planet from an equatorial view approximately 22,300 miles above the surface of the Earth.

NOAA’s satellites are the backbone of its life-saving weather forecasts. GOES-16 will build upon and extend the more than 40-year legacy of satellite observations from NOAA that the American public has come to rely upon.

NASA is planning human spaceflight missions further out into space and is learning how astronauts adapt to life off Earth for months and years at a time. The International Space Station provides the laboratory environment for numerous studies into how the human body reacts when exposed to microgravity.

Flight Engineer Thomas Pesquet, from the European Space Agency, is wearing the new SkinSuit to study its ability to offset the effects of living in space including back pain and spine-stretching. The unique, tailor-made suit squeezes the body from the shoulder to the feet mimicking the force felt on Earth. Pesquet is evaluating the SkinSuit’s comfort, range of motion and its functionality while exercising.

Image above: The aurora is pictured as the International Space Station orbits Earth during a nighttime pass. Image Credit: NASA.

Lighting is also very important when living in space since the daily sunrise and sunset cycle that guides life on Earth no longer applies. The crew is participating in tests helping researchers understand how new station lights that can be adjusted for intensity and wavelength are affecting crew sleep patterns and cognitive performance.

The cosmonauts, Oleg Novitskiy, Andrey Borisenko and Sergey Ryzhikov, were conducting their own set of human research experiments today. The trio collected blood and saliva samples to explore how the immune system and bone mass is affected in outer space. The samples were stowed in a U.S. science freezer for later analysis on Earth.

BEAM was opened for a short time Thursday so the crew could install sensors inside the expandable module. The Expedition 50 space residents also explored how the body changes shape and how to prevent back pain during long-term missions.

BEAM, the Bigelow Expandable Activity Module, had its hatches opened temporarily so astronaut Peggy Whitson could install temporary sensors and perform a modal test, which has the astronaut use their fist to impart loads on the module. The sensors are measuring the resulting vibrations and how the module holds up to impacts. BEAM is an expandable habitat technology demonstration, which is a lower-mass and lower-volume system than metal habitats and can increase the efficiency of cargo shipments, possibly reducing the number of launches needed and overall mission costs.

Yamzho Yumco (Sacred Swan) Lake in Tibet is surrounded by snow-capped mountains and is one of the three largest sacred lakes. It is highly crenellated with many bays and inlets. The lake is home to Samding Monastery, headed by a female re-incarnation (Wikipedia). The image was acquired March 6, 2014, covers an area of 49.8 by 60 km, and is centered at 28.9 degrees north, 90.6 degrees east.

With its 14 spectral bands from the visible to the thermal infrared wavelength region and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched Dec. 18, 1999, on Terra. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and data products.

The Calabash Nebula, pictured here — which has the technical name OH 231.8+04.2 — is a spectacular example of the death of a low-mass star like the sun. This image taken by the NASA/ESA Hubble Space Telescope shows the star going through a rapid transformation from a red giant to a planetary nebula, during which it blows its outer layers of gas and dust out into the surrounding space. The recently ejected material is spat out in opposite directions with immense speed — the gas shown in yellow is moving close to one million kilometers per hour (621,371 miles per hour).

Astronomers rarely capture a star in this phase of its evolution because it occurs within the blink of an eye — in astronomical terms. Over the next thousand years the nebula is expected to evolve into a fully-fledged planetary nebula.

The nebula is also known as the Rotten Egg Nebula because it contains a lot of sulphur, an element that, when combined with other elements, smells like a rotten egg — but luckily, it resides over 5,000 light-years away in the constellation of Puppis.

Climate change-driven glacial melt is causing landslides in alpine regions. Data from the Sentinel-1 satellite mission are being inserted into a new cloud computing system to monitor such hazards globally.

Aletsch Glacier

The Aletsch Glacier, the largest in the Alps, is experiencing an average retreat of about 50 m a year. The adjacent rocks that were previously constrained by the ice mass are progressively being released, generating slope instabilities. For this reason, the Aletsch region is a unique place where scientists can investigate how changes in glaciers affect the long- and short-term evolution of rock slope stability.

To monitor the progressive changes occurring throughout a 2 sq km area southeast of the glacier – called the Moosfluh slope – the Chair of Engineering Geology at the Swiss Federal Institute of Technology in Zurich (ETHZ) installed ground-based instruments in 2013.

Between September and October 2016, Moosfluh experienced an abnormal acceleration. The deformation generated several deep cracks and rock failures, hindering access to hiking paths visited by tourists, and affecting a cable car station located near the crest of the slope.

Moosfluh slope instability

To investigate the extent of the landslide further, radar images from the Copernicus Sentinel-1 satellite mission over August to November 2016 were analysed with the ESA’s Geohazards Exploitation Platform – or GEP – to produce a velocity map of the unstable area.

The satellite data also helped scientists to define the most active areas and identify locations to place additional instruments on the ground.

“With the help of satellite data and of GEP, we have improved our capability to monitor the spatial evolution of surface displacements at Moosfluh, as well as to provide a better interpretation of the ongoing physical processes during the critical phase,” said Andrea Manconi from ETHZ.

Sentinel-1

GEP is one of six Thematic Exploitation Platforms – or TEPs – developed by ESA to serve data-user communities.

These cloud-based platforms provide an online venue to access information, processing tools and computing resources for collaboration, allowing for knowledge to be extracted from the large environmental datasets produced through Europe’s Copernicus programme and from other Earth-observing satellites.

Geohazards TEP

The two-satellite Copernicus Sentinel-1 mission is particularly useful for monitoring geophysical hazards like landslides. The satellites each carry a radar sensor that can detect small changes in the ground between each overflight, every 6–12 days.

The frequency of Sentinel-1’s data acquisition paired with GEP’s processing tools may allow for the quick detection of slope instabilities and their consequential risks.

jeudi 2 février 2017

Impact ejecta is material that is thrown up and out of the surface of a planet as a result of the impact of an meteorite, asteroid or comet. The material that was originally beneath the surface of the planet then rains down onto the environs of the newly formed impact crater.

Some of this material is deposited close to the crater, folding over itself to form the crater rim, visible here as a yellowish ring. Other material is ejected faster and falls down further from the crater rim creating two types of ejecta: a "continuous ejecta blanket" and "discontinuous ejecta." Both are shown in this image. The blocky area at the center of the image close to the yellowish crater rim is the "continuous" ejecta. The discontinuous ejecta is further from the crater rim, streaking away from the crater like spokes on a bicycle.

A new mosaic from ESA’s Mars Express shows off the Red Planet’s north polar ice cap and its distinctive dark spiralling troughs.

The mosaic was generated from 32 individual orbit ‘strips’ captured between 2004 and 2010, and covers an area of around a million square kilometres.

The ice cap is a permanent fixture, but in the winter season – as it is
now in early 2017 – temperatures are cold enough for around 30 percent
of the carbon dioxide in the planet’s atmosphere to precipitate onto the
cap, adding a seasonal layer up to a metre thick.

Mars north polar ice cap in context

During the warmer summer months most of the carbon dioxide ice turns directly into gas and escapes into the atmosphere, leaving behind the water-ice layers.

Strong winds are thought to have played an important role in shaping the ice cap over time, blowing from the elevated centre towards its lower edges and twisted by the same Coriolis force that causes hurricanes to spiral on Earth.

One particularly prominent feature is a 500 km-long, 2 km-deep trench that almost cuts the cap in two.

Colour mosaic of Mars north polar ice cap

The plunging canyon, known as Chasma Boreale, is thought to be a relatively old feature, forming before the ice–dust spiral features, and seemingly growing deeper as new ice deposits built up around it.

Subsurface investigations by radar instruments onboard Mars Express and NASA’s Mars Reconnaissance Orbiter revealed that the ice cap is made up of many individual layers of ice and dust extending to a depth of around 2 km.

Perspective view of Chasma Boreale

This presents a valuable record for the nature of how the planet’s climate has changed as its tilt and orbit varied over hundreds of thousands of years.

mercredi 1 février 2017

This week in 1964, SA-5, the fifth Saturn I launch vehicle launched from NASA's Kennedy Space Center. SA-5 marked a number of firsts in the Saturn development program -- which was managed by NASA's Marshall Space Flight Center -- including the first flight of a Saturn I Block II vehicle; the first flight of a live S-IV second stage with a cluster of six liquid hydrogen-fueled RL-10 engines, the first successful second stage separation and the first use of Launch Complex 37. The Saturn I launch vehicle was built at Marshall's Fabrication and Assembly Engineering Division.

Marshall also designed, developed and managed the production of the Saturn V rocket that took astronauts to the moon. Today, Marshall is developing NASA's Space Launch System, the most powerful rocket ever built that will be capable of sending astronauts deeper into space than ever before, including to an asteroid and Mars. The NASA History Program is responsible for generating, disseminating, and preserving NASA’s remarkable history and providing a comprehensive understanding of the institutional, cultural, social, political, economic, technological, and scientific aspects of NASA’s activities in aeronautics and space. For more pictures like this one and to connect to NASA’s history, visit the Marshall History Program’s webpage. (NASA): https://www.nasa.gov/centers/marshall/history/index.html

This dune field formed near the base of the North Polar cap. Dunes require a source of loose particulate material to form. The source of the northern dune fields around the polar cap may be from the layers of dusty ice that are eroded by strong polar winds.

This image was taken during the Martian northern summer, so there is no frost present on the dunes. The dunes closest to the base of the polar cap are long and parallel, indicating strong winds from the direction of the cap. As they get farther away from the polar cap, they start to form more crescent shaped dunes, called barchan dunes.

Repeated observations by HiRISE of dunes like these show measurable changes in some locations. This discovery adds to the growing evidence that there are active processes happening all over the surface of Mars today.

Telemetry confirming that the engine burn went as planned reached the New Horizons mission operations center at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, via NASA’s Deep Space Network stations in Goldstone, California and Canberra, Australia, shortly after 1:15 p.m. EST. The radio signals carrying the data traveled over 3.5 billion miles (5.6 billion kilometers) and took more than five hours to reach Earth at the speed of light.

Image above: What’s Next for New Horizons? The red line marks the path of the New Horizons toward its next flyby, a Kuiper Belt object known as 2014 MU69. The green dot approximates the spacecraft’s current position. Image Credits: NASA/JHUAPL/SwRI.

Operating by timed commands stored on its computer, New Horizons fired its thrusters for just 44 seconds, adjusting its velocity by about 44 centimeters per second, or a little less than one mile per hour. It was the first trajectory maneuver since the team conducted a set of four maneuvers in the fall of 2015 that put the spacecraft on a course for its rendezvous with MU69 on Jan. 1, 2019.

“One mile per hour may not sound like much,” said mission Principal Investigator Alan Stern, of the Southwest Research Institute in Boulder, Colorado, “but over the next 23 months, as we approach MU69, that maneuver will add up to an aim point refinement of almost six thousand miles (10,000 kilometers).”

New Horizons Mission Design Lead Yanping Guo, of APL, said Wednesday’s burn adjusts for what the team has learned since 2015 from new Hubble Space Telescope measurements of MU69’s orbit, as well as the spacecraft’s own location.

After the burn the spacecraft transitioned out of a so-called “three-axis stabilized mode,” the operating mode that allowed New Horizons to make new telescopic observations of six KBOs over the past week. These science observations will reveal new information on the shapes, surface properties and satellite systems of these objects, in ways that can’t be done from Earth. Images from these studies will be transmitted to Earth in the coming weeks.

At the time of closest approach (called perijove), Juno will be about 2,670 miles (4,300 kilometers) above the planet's cloud tops and traveling at a speed of about 129,000 mph (57.8 kilometers per second) relative to the gas giant. All of Juno's eight science instruments, including the Jovian Infrared Auroral Mapper (JIRAM) instrument, will be on and collecting data during the flyby.

"Tomorrow may be 'Groundhog Day' here on Earth, but it's never Groundhog Day when you are flying past Jupiter,” said Scott Bolton, principal investigator of Juno from the Southwest Research Institute in San Antonio. "With every close flyby we are finding something new."

The Juno science team continues to analyze returns from previous flybys. Revelations include that Jupiter's magnetic fields and aurora are bigger and more powerful than originally thought and that the belts and zones that give the gas giant’s cloud top its distinctive look extend deep into the planet’s interior. Peer-reviewed papers with more in-depth science results from Juno’s first three flybys are expected to be published within the next few months. Also, JunoCam, the first interplanetary outreach camera, is now being guided with the assistance from the public -- people can participate by voting for what features on Jupiter should be imaged during each flyby.

Juno is currently in a 53-day orbit period around Jupiter as the team evaluates options for performing a maneuver to get the spacecraft into a shorter orbit period. While the initial plan was for the mission was to have 14-day orbits during this time, Juno can reveal amazing details about Jupiter even if it stays in the longer orbits for the duration of the mission.

Juno launched on Aug. 5, 2011, from Cape Canaveral, Florida, and arrived at Jupiter on July 4, 2016. During its mission of exploration, Juno soars low over the planet's cloud tops -- as close as about 2,600 miles (4,100 kilometers). During these flybys, Juno is probing beneath the obscuring cloud cover of Jupiter and studying its auroras to learn more about the planet's origins, structure, atmosphere and magnetosphere.

Artist's view of the Juno spacecraft. Image Credit: NASA

NASA's Jet Propulsion Laboratory, Pasadena, California, manages the Juno mission for the principal investigator, Scott Bolton, of Southwest Research Institute in San Antonio. The Juno mission is part of the New Frontiers Program managed by NASA's Marshall Space Flight Center in Huntsville, Alabama, for the Science Mission Directorate. Lockheed Martin Space Systems, Denver, built the spacecraft. JPL is a division of Caltech in Pasadena, California.

Astronomers have for a long time studied the glowing, cosmic clouds of gas and dust catalogued as NGC 6334 and NGC 6357, this gigantic new image from ESO’s Very Large Telescope Survey Telescope being only the most recent one. With around two billion pixels this is one of the largest images ever released by ESO. The evocative shapes of the clouds have led to their memorable names: the Cat’s Paw Nebula and the Lobster Nebula, respectively.

NGC 6334 is located about 5500 light-years away from Earth, while NGC 6357 is more remote, at a distance of 8000 light-years. Both are in the constellation of Scorpius (The Scorpion), near the tip of its stinging tail.

Highlights from VST image of Cat’s Paw and Lobster Nebulae

The British scientist John Herschel first saw traces of the two objects, on consecutive nights in June 1837, during his three-year expedition to the Cape of Good Hope in South Africa. At the time, the limited telescopic power available to Herschel, who was observing visually, only allowed him to document the brightest “toepad” of the Cat’s Paw Nebula. It was to be many decades before the true shapes of the nebulae became apparent in photographs — and their popular names coined.

The three toepads visible to modern telescopes, as well as the claw-like regions in the nearby Lobster Nebula, are actually regions of gas — predominantly hydrogen — energised by the light of brilliant newborn stars. With masses around 10 times that of the Sun, these hot stars radiate intense ultraviolet light. When this light encounters hydrogen atoms still lingering in the stellar nursery that produced the stars, the atoms become ionised. Accordingly, the vast, cloud-like objects that glow with this light from hydrogen (and other) atoms are known as emission nebulae.

The star formation regions NGC 6334 and NGC 6357 in the constellation of Scorpius

Thanks to the power of the 256-megapixel OmegaCAM camera, this new Very Large Telescope Survey Telescope (VST) image reveals tendrils of light-obscuring dust rippling throughout the two nebulae. At 49511 x 39136 pixels this is one of the largest images ever released by ESO.

OmegaCAM is a successor to ESO’s celebrated Wide Field Imager (WFI), currently installed at the MPG/ESO 2.2-metre telescope on La Silla. The WFI was used to photograph the Cat’s Paw Nebula in 2010, also in visible light but with a filter that allowed the glow of hydrogen to shine through more clearly (eso1003). Meanwhile, ESO’s Very Large Telescope has taken a deep look into the Lobster Nebula, capturing the many hot, bright stars that influence the object’s colour and shape (eso1226).

Zooming in on the Cat’s Paw and Lobster Nebulae

Despite the cutting-edge instruments used to observe these phenomena, the dust in these nebulae is so thick that much of their content remains hidden to us. The Cat’s Paw Nebula is one of the most active stellar nurseries in the night sky, nurturing thousands of young, hot stars whose visible light is unable to reach us. However, by observing at infrared wavelengths, telescopes such as ESO’s VISTA can peer through the dust and reveal the star formation activity within.

Viewing nebulae in different wavelengths (colours) of light gives rise to different visual comparisons on the part of human observers. When seen in longer wavelength infrared light, for example, one portion of NGC 6357 resembles a dove, and the other a skull; it has therefore acquired the additional name of the War and Peace Nebula.

Panning across the Cat’s Paw and Lobster Nebulae

More information:

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

A space debris avoidance manoeuvre planned for ESA’s Swarm mission proved unnecessary last week, but the close encounter highlighted the growing risk from space debris.

It’s an increasingly common occurrence: ESA’s Space Debris Office starts monitoring a piece of debris – there are over 22 000 tracked in space now – that could pass near one of the Agency’s satellites.

One of the Swarm

Additional tracking data indicate the object – maybe a chunk of some old satellite already long abandoned – might pass too close, within the ‘risk threshold’ that surrounds each active spacecraft.

Upon closer look, uncertainty in the object’s track combined with uncertainty in the satellite’s orbit mean that a collision cannot be excluded. The only solution is for mission controllers to boost the satellite out of harms’ way. It’s time to take action.

Conjunction alert

This is exactly what happened on 24 January, when space debris experts at ESA’s mission control centre in Darmstadt, Germany, alerted the Swarm flight control team that one of their three satellites, Swarm-B, would have a close call from a 15 cm chunk of the former Cosmos 375.

Launched in 2013, the trio of Swarm satellites are measuring and untangling the different magnetic fields that stem from Earth’s core, mantle, crust, oceans, ionosphere and magnetosphere.

ESA control room

The close encounter between Swarm-B and the debris was forecast to take place on 25 January at 23:11 GMT on the following day.

At that point, a ‘team of teams’ began taking action to assess the situation, plan a debris avoidance manoeuvre and upload a set of commands to execute the manoeuvre – all before the forecast flyby just 39 hours away.

The situation was complicated by the fact that there were only two communication slots – a radio link established when Swarm-B flies over its ground station at Kiruna, Sweden – prior to the flyby.

Taking action

Following a first coordination meeting on Tuesday morning, engineers from the Swarm mission control team began working with specialists from flight dynamics, from the Space Debris Office and from the Swarm project team at ESA’s centre near Rome to prepare the manoeuvre.

Following a detailed analysis by the flight dynamics and space debris experts, it was determined that boosting Swarm-B higher in its orbit by about 35 m would do the trick.

“There was at this point still some uncertainty in our knowledge of the debris object’s trajectory, but we were confident that this boost would reduce the risk of a too-near flyby, or even an actual collision, to below the acceptable threshold set by the mission managers,” said Holger Krag Head of ESA’s Space Debris Office.

The boost would require the satellite to fire its cold-gas thrusters for about 44 seconds.

Flight control engineers used data files provided by flight dynamics to prepare a set of commands for upload to Swarm-B. The craft would be commanded to shut down its science instruments, reorient itself in space, execute the manoeuvre on its own (out of contact with ground) and then reconfigure to resume science, all overnight between 25–26 January, starting around 45 minutes before the encounter.

Just after breakfast on Wednesday morning, 15 hours before the flyby, the commands were uplinked, fully enabled and ready to execute automatically without any further action from mission control.

“This was a good plan, and it had the primary aim of ensuring spacecraft safety now and to provide some good margin against a possible future encounter with this debris object,” said Swarm mission manager Rune Floberghagen.

Gathering the latest facts

On Wednesday morning, however, two new batches of information were received. First, during the same ground station communication slot when the manoeuvre commands were being uploaded, Swarm-B also sent down a fresh set of GPS data recorded during the previous 20 hours. The highly precise data provided a record of the satellite’s actual current orbit.

“This allowed us to make a fresh orbit determination and prediction, and this could be used to reduce uncertainty in the satellite’s position at the forecast conjunction time this evening to very small values,” said Detlef Sieg, the flight dynamics specialist assigned to Swarm.

Second, the Space Debris Office received a fresh set of tracking information from the debris tracking radar system operated by the US armed forces, providing new and more precise data on the impending object’s orbital trajectory.

Space navigators at work

“As this was acquired less than 24 hours prior to the forecast conjunction, it had lower uncertainty related to the object’s position during the conjunction than previous tracking data,” said Klaus Merz an analyst in the Space Debris Office.

Klaus and his team ran a number of detailed manual calculations using the new object tracking data and ESA’s own debris assessment software tools, assessing the risk of a collision if the avoidance manoeuvre was performed – and if one was not.

“As a result of the reduced uncertainties in the object’s trajectory, the risk of collision is now well below the mission’s threshold,” said Klaus.

Last chance to abort

Knowing that time was crucial, mission manager Rune Floberghagen asked everyone for their recommendations at a final ‘go/no-go’ meeting at 10:40 GMT on Wednesday morning.

With close flyby now no longer presenting an unacceptable risk, it was clear the satellite could be left in its current orbit.

“Further, we could confirm that removing the uploaded commands could be done in a very safe way and would have no effect on the continuing operation of Swarm,” said spacecraft operations manager Elia Maestroni.

Swarm trio in orbit

“Therefore the decision was taken to abort the manoeuvre and return the satellite to its usual science-gathering timeline.”

And Swarm-B – a marvellous satellite on a vital science mission 500 km above our heads – continued safely on its way, oblivious to all the human activity focused on its wellbeing in the past 36 hours.

The future is now

“In the end, the situation this week turned out not to need a debris avoidance manoeuvre,” said Holger.

“While this is the case with the majority of initial alerts, we are nonetheless seeing an increase in the number of avoidance manoeuvres that must be fully executed.”

Sentinel-1 impact event 2016

At ESA’s Space Debris Office, the number of potential conjunction events that must be analysed for a mission like Swarm is several hundred per year. Of these, typically 10 turn out to be critical and deserve particular attention.

With additional updates leading to improved orbit information – like this one with Swarm-B – most of these occurrences turn out to be false alerts. Ultimately, a typical Earth observation mission has to conduct a collision manoeuvre once or twice a year.

Compared to the situation before 2007 (when a Chinese satellite fragmented in orbit during an antisatellite missile test and before the collision between Iridium-33 and Cosmos-2251 happened), this is roughly a duplication of the avoidance actions.

“This highlights the need for all space-faring organisations to strictly follow debris mitigation guidelines that aim to limit the creation of new debris,” said Holger.

“The current space debris situation is already at a ‘tipping point’ in some orbits. This requires urgent action.”

mardi 31 janvier 2017

The LHCb experiment has found hints of what could be a new piece of the jigsaw puzzle of the missing antimatter in our universe. They have found tantalising evidence of a phenomenon dubbed charge-parity (CP) violation in particles known as baryons – a family of particles whose best-known members are the protons and neutrons that make up all the matter in the universe.

The idea that the baryons made of matter behave exactly like their antimatter counterparts is related to the idea of CP symmetry. Any violation of this symmetry would imply that the laws of physics are not the same for matter and antimatter particles.

This is important because a detailed understanding of how this symmetry is violated in nature can contribute to explaining the overwhelming excess of matter over antimatter observed in our universe, despite the fact that the Big Bang should have created equal amounts of matter and antimatter in the first place.

The Standard Model (SM) of particle physics predicts that a tiny amount of CP violation exists also in the baryon sector. Although CP-violating processes have been studied for over 50 years, no significant effects had been seen with baryonic particles. Moreover, CP violation as described in the SM is not large enough to account for the much larger matter-antimatter unbalance. Therefore, other CP violation sources must contribute, and one of the main goals of LHCb is precisely to search for new sources of CP violation.

The new LHCb result is based on an analysis of data collected during the first three years of the Large Hadron Collider (LHC) operations. Among all the possible short-living particles created as a result of a proton-proton collision, the collaboration compared the behavior of the Λb0 baryon and its antimatter counterpart, Λb0 -bar, when they decay into a proton (or antiproton) and three charged particles called pions. This process is extremely rare and has never previously been observed. The high production rate of these baryons at the LHC and the specialised capabilities of the LHCb detector allowed the collaboration to collect a pure sample of around 6000 such decays.

The LHCb collaboration compared the distribution of the four decay products of the Λb0 and Λb0 -bar baryons and computed specific quantities that are sensitive to the CP symmetry. Any significant difference, or asymmetry, between such quantities for the matter and antimatter cases would be a manifestation of CP violation.

The LHCb data revealed a significant level of asymmetries in those CP-violation-sensitive quantities for the Λb0and Λb0-bar baryon decays, with differences in some cases as large as 20%.

Overall, the statistical significance – which is how physicists refer to the probability that this result hasn’t occurred by chance – is at the level of 3.3 standard deviations, and a discovery is claimed when this value reaches 5 standard deviations. These results, published today in Nature Physics, will soon be updated with the larger data set collected so far during the second run of the LHC. If this earlier evidence for CP violation is seen again with greater significance in the larger sample, the result will be an important milestone in the study of CP violation.

CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.

The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.

Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 22 Member States.

Scientists observing a curious neutron star in a binary system known as the 'Rapid Burster' may have solved a forty-year-old mystery surrounding its puzzling X-ray bursts. They discovered that its magnetic field creates a gap around the star, largely preventing it from feeding on matter from its stellar companion. Gas builds up until, under certain conditions, it hits the neutron star all at once, producing intense flashes of X-rays. The discovery was made with space telescopes including ESA's XMM-Newton.

Discovered in the 1970s, the Rapid Burster is a binary system comprising a low-mass star in its prime and a neutron star – the compact remnant of a massive star's demise. In such a stellar pair, the gravitational pull of the dense remnant strips the other star of some of its gas; the gas forms an accretion disc and spirals towards the neutron star.

As a result of this accretion process, most neutron star binaries continuously release large amounts of X-rays, which are punctuated by additional X-ray flashes every few hours or days. Scientists can account for these 'type-I' bursts, in terms of nuclear reactions that are ignited in the inflowing gas – mainly hydrogen – when it accumulates on the neutron star's surface.

But the Rapid Burster is a peculiar source: at its brightest, it does emit these type-I flashes, while during periods of lower X-ray emission, it exhibits the much more elusive 'type-II' bursts – these are sudden, erratic and extremely intense releases of X-rays.

In contrast to type-I bursts, which do not represent a significant release of energy with respect to what is normally emitted by the accreting neutron star, bursts of type-II liberate enormous amounts of energy during periods otherwise characterised by very little emission occurring [1].

Despite forty years of searches, type-II bursts have been detected only in one other source besides the Rapid Burster. Known as the Bursting Pulsar and discovered in the 1990s, this binary system comprises a low-mass star and a highly magnetized, spinning neutron star – a pulsar – that exhibits only type-II bursts.

Because of the scarcity of sources that display this phenomenon, the underlying physical mechanisms have long been debated, but a new study of the Rapid Burster provides first evidence for what is occurring.

"The Rapid Burster is the archetypal system to investigate type-II bursts – it's where they were first observed and the only source that shows both type-I and type-II bursts," says Jakob van den Eijnden, a PhD student at the Anton Pannekoek Institute for Astronomy in Amsterdam, The Netherlands, and lead author of a Letter published in Monthly Notices of the Royal Astronomical Society.

In this study, Jakob and his colleagues organised an observing campaign using three X-ray space telescopes to find out more about this system.

Under the coordination of co-author Tullio Bagnoli, who was also based at the Anton Pannekoek Institute for Astronomy, the team managed to observe the source bursting over a few days in October 2015 with a combination of NASA's NuSTAR and Swift, and ESA's XMM-Newton.

They first monitored the source with Swift, timing the observations for a period when they expected a series of type-II bursts to take place. Then, soon after the first burst was detected, the scientists set the other observatories into motion, using XMM-Newton to measure X-rays emitted directly by the neutron star's surface or by gas in the accretion disc, and NuSTAR to detect higher-energy X-rays, which are emitted by the neutron star and reflected off the disc.

With these data, the scientists scrutinised the structure of the accretion disc to understand what happens to it before, during, and after these copious releases of X-rays.

According to one model, type-II bursts occur because the fast spinning magnetic field of the neutron star keeps the gas flowing from the companion star at bay, preventing it from reaching closer to the neutron star and effectively creating an inner edge at the centre of the disc. However, as the gas continues to flow and accumulate near this edge, it spins faster and faster, and eventually catches up with the spinning velocity of the magnetic field.

"It's as if we threw something towards a merry-go-round that is spinning very fast: it would bounce off, unless it's thrown at the same velocity as the machine," explains Jakob.

"A similar balancing act happens between the inflowing gas and the spinning magnetic field: as long as the gas hasn't the right speed, it cannot get to the neutron star and it can only pile up at the edge. By the time it reaches the right velocity, a lot of gas has accumulated and it hits the neutron star all at once, giving rise to the dramatic emission of type-II bursts."

This model predicts that, while the material is piling up, a gap should form between the neutron star and the edge of the accretion disc.

In other models, the intense flashes are explained as arising from instabilities in the flow of the accreting gas or from general-relativistic effects. In either case, these would take place much closer to the neutron star and not give rise to such a gap.

"A gap is exactly what we found at the Rapid Burster," says Nathalie Degenaar, a researcher at Anton Pannekoek Institute for Astronomy and Jakob's PhD advisor. "This strongly suggests that the type-II bursts are caused by the magnetic field."

The observations indicate that there is a gap of roughly 90 km between the neutron star and the inner edge of the accretion disc. While not impressive on cosmic scales, the size of the gap is much larger than the neutron star itself, which has a radius of about 10 km.

This finding is in line with results from a previous study by Nathalie and collaborators, who had observed a similar gap around the Bursting Pulsar – the other source known to produce type-II bursts.

In the new study of the Rapid Burster, the scientists also measured the strength of the neutron star's magnetic field: at 6 × 108 G, it is around a billion times stronger than Earth's and, most important, over five times stronger than observed in other neutron stars with a low-mass stellar companion. This could hint at a young age of this binary system, suggesting that the accretion process has not been going on for long enough to damp the magnetic field down, as is thought to have happened in similar systems.

If this neutron star binary really is as young as its strong magnetic field indicates, then it is expected to spin much slower than its older counterparts: future measurements of the star's spinning rate might help confirm this unusual scenario.

"This result is a big step towards solving a forty-year-old puzzle in neutron star astronomy, while also revealing new details about the interaction between magnetic fields and accretion discs in these exotic objects," concludes Norbert Schartel, XMM-Newton Project Scientist at ESA.

Notes:

[1] The relative energy output of a burst with respect to the normal accretion process is tens to hundreds of times higher in type-II bursts than in type-I bursts.

Preliminary research results for the NASA Twins Study debuted at NASA’s Human Research Program’s annual Investigators’ Workshop in Galveston, Texas the week of January 23. NASA astronaut Scott Kelly returned home last March after nearly one year in space living on the International Space Station. His identical twin brother, Mark, remained on Earth.

Researchers found this to be a great opportunity for a nature versus nurture study, thus the Twins Study was formed. Using Mark, a retired NASA astronaut, as a ground-based control subject, ten researchers are sharing biological samples taken from each twin before, during and after Scott’s mission. From these samples, knowledge is gained as to how the body is affected by extended time in space. These studies are far from complete. Additional research analysis is in process.

Image above: Twins Study Investigators. Image Credit: NASA.

Mike Snyder, the Integrated Omics investigator, reported altered levels of a panel of lipids in Scott (the flight twin) that indicate inflammation. Additionally, there was an increased presence of 3-indolepropionic (IPA) in Mark (the ground-based twin). This metabolite is known to be produced only by bacteria in the gut and is being investigated as a potential brain antioxidant therapeutic. IPA is also known to help maintain normal insulin activity to regulate blood sugar after meals.

Susan Bailey’s investigation focuses on Telomeres and Telomerase. It is understood that when looked at over many years, telomeres decrease in length as a person ages. Interestingly, on a time scale of just one year, Bailey found Scott’s telomeres on the ends of chromosomes in his white blood cells increased in length while in space. This could be linked to increased exercise and reduced caloric intake during the mission. However, upon his return to Earth they began to shorten again. Interestingly, telomerase activity (the enzyme that repairs the telomeres and lengthens them) increased in both twins in November, which may be related to a significant, stressful family event happening around that time.

Mathias Basner’s study, Cognitive Performance in Spaceflight, is looking at cognition, especially the difference found during a 12-month mission as compared to six-month missions. Following the one-year mission, he found a slight decrease in speed and accuracy post mission. Overall, however, the data does not support a relevant change in cognitive performance inflight by increasing the mission duration from six to 12 months.

Image above: Identical twins, Scott and Mark Kelly, are the subjects of NASA’s Twins Study. Scott (left) spent a year in space while Mark (right) stayed on Earth as a control subject. Researchers are looking at the effects of space travel on the human body. Image Credit: NASA.

In the Biochemical Profile investigation, headed by Scott Smith, there appeared to be a decline in bone formation during the second half of Scott’s mission. Also, by looking at C Reactive Protein levels (a widely accepted biochemical marker for inflammation), there appeared to be a spike in inflammation soon after landing, likely related to the stresses of reentry and landing. The stress hormone Cortisol was low normal throughout the one-year mission, but IGF-1 hormone levels increased over the course of the year. This hormone is implicated with bone and muscle health and was likely impacted by heavy exercise countermeasures during flight.

Fred Turek’s focus is on the Microbiome in the GI Tract – or “bugs” naturally found in the gut to aid in digestion. Differences in the viral, bacterial, and fungal microbiome between the twins were pronounced at all time points; however, this was expected due to their differing diet and environment. Of interest were the differences in microbial species observed in Scott on the ground versus his time in space. One shift was a change in ratio of two dominant bacterial groups (i.e., Firmicutes and Bacteroidetes) present in his GI tract. The ratio of one group to the other increased during flight and returned to pre-flight levels upon return to Earth.

Emmanuel Mignot’s investigation, Immunome Studies, looks at changes in the body before and after a flu vaccine was administered to each twin. Following flu vaccines, “personalized” T cell receptors were created. These unique T cell receptors increased in both twins which was the expected immune response that protects from catching the flu.

Chris Mason is performing Genome Sequencing on the DNA and RNA contained within the twins’ white blood cells with his investigation. Whole genome sequencing was completed and showed each twin has hundreds of unique mutations in their genome, which are normal variants. RNA (transcriptome) sequencing showed more than 200,000 RNA molecules that were expressed differently between the twins. They will look closer to see if a “space gene” could have been activated while Scott was in space.

Image above: Students at Odyssey Academy in Galveston competed in an art contest depicting the Twins Study. Perla Zuniga won 2nd Place with her portrayal of the Kelly Twins as two in one: the spaceman and the Earthling. Image Credit: NASA.

Andy Feinberg studies Epigenomics, or how the environment regulates our gene expression. In the DNA within Scott’s white blood cells, he found that the level of methylation, or chemical modifications to DNA, decreased while inflight – including a gene regulating telomeres, but returned to normal upon return. On the ground, Mark’s level of methylation in the DNA derived from his white blood cells increased at midpoint in the study but returned to normal in the end. Variability was observed in the methylation patterns from both twins; however, this epigenetic noise was slightly higher in Scott during spaceflight and then returned to baseline levels after return to Earth. These results could indicate genes that are more sensitive to a changing environment whether on Earth or in space.

Through further research integrating these preliminary findings, in coordination with other physiological, psychological, and technological investigations, NASA and its partners will continue to ensure that astronauts undertake future space exploration missions safely, efficiently and effectively. A joint summary publication is planned for later in 2017, to be followed by investigator research articles.

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NASA's Human Research Program enables space exploration by reducing the risks to human health and performance through a focused program of basic, applied, and operational research. This leads to the development and delivery of: human health, performance, and habitability standards; countermeasures and risk mitigation solutions; and advanced habitability and medical support technologies.